DEVFS_CDEVPRIV LOCAL DEVFS_CDEVPRIV
devfs_set_cdevpriv, devfs_get_cdevpriv, devfs_clear_cdevpriv — manage
per-open filedescriptor data for devices
typedef void (*cdevpriv_dtr_t)(void *data);
devfs_set_cdevpriv(void *priv, cdevpriv_dtr_t dtr);
The devfs_xxx_cdevpriv() family of functions allows the cdev driver meth‐
ods to associate some driver-specific data with each user process open(2)
of the device special file. Currently, functioning of these functions is
restricted to the context of the cdevsw switch method calls performed as
devfs(5) operations in response to system calls that use filedescriptors.
The devfs_set_cdevpriv() function associates a data pointed by priv with
current calling context (filedescriptor). The data may be retrieved
later, possibly from another call performed on this filedescriptor, by
the devfs_get_cdevpriv() function. The devfs_clear_cdevpriv() disassoci‐
ates previously attached data from context. Immediately after
devfs_clear_cdevpriv() finished operating, the dtr callback is called,
with private data supplied data argument.
On the last filedescriptor close, system automatically arranges
If successful, the functions return 0.
The function devfs_set_cdevpriv() returns the following values on error:
[ENOENT] The current call is not associated with some
[EBUSY] The private driver data is already associated with
The function devfs_get_cdevpriv() returns the following values on error:
[EBADF] The current call is not associated with some
[ENOENT] The private driver data was not associated with cur‐
rent filedescriptor, or devfs_clear_cdevpriv() was
SEE ALSOopen(2), close(2), devfs(5), kern_openat(9)HISTORY
The devfs_cdevpriv() family of functions first appeared in FreeBSD 7.1.
BSD September 8, 2008 BSD